[carlosm] Fix general search to perform searches by fragment of texts. Add...

Resolves chebi-elasticsearch#27 (closed) and #43 (closed)

• Users should perform searches using fragments of text, for example, caff should get the caffeine compound.

• It is really important to create unit tests for the searches executed in the main bar (general search), so I created a set of unit tests which includes: chebi ids, iupac names, brand names, chebi names, formula, smiles, inchi, inchikey, wildcards, cross-references, fragment texts, definition, etc. We could add more tests later.

• This change has security impacts (if so, add them to the description)

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

• This change requires a documentation update

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README, Confluence etc.)
• My changes generate no new warnings in the build
• I have added tests that prove my fix is effective or that my feature works
• My code does not decrease pylint score

Dependencies

• This Merge Request is dependent on any other Merge Request or configuration or some ticket; please mention here
• Includes migration
• Installs new requirement

Post Review

• Squash and merge feature_branch to staging
• Delete branch after merge

Additional Description

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